An “explosion” of cases in which greedy relatives commit fraud by targeting members of their own family provides further evidence of why assisted suicide should not be legalised, say disabled activists.

One of the strongest arguments for opposing legalisation is the risk that it will lead to some family members pressurising terminally-ill relatives to end their lives early in order to benefit from an inheritance.

Research published this week by accountancy giant KPMG reveals an “explosion of cases in which individuals, betraying the trust of those closest to them, targeted their own relatives”.

The latest survey, which looked at January to June 2015, found that fraud within families grew by 384 per cent compared to the same period last year.

Hitesh Patel, UK forensic partner at KPMG, said: “People are living longer, and we are seeing examples of people who are choosing to remove uncertainties about when or if they will get their inheritance by fraudulent means.

“It’s also likely these cases are just the tip of the iceberg – frauds of this nature often go unreported as embarrassed victims seek to ‘keep it in the family’ and ‘forgive and forget’.”

The latest attempt by the euthanasia lobby to persuade parliament to legalise assisted suicide will reach its next key stage on 11 September, when the assisted dying bill, proposed by Labour MP Rob Marris, is debated and voted on in the Commons.

Sir Bert Massie (pictured), former chair of the Disability Rights Commission, said the “objective” KPMG report has “strong implications” for the battle to avoid legalisation, and “needs feeding into the debate”.

He said the survey highlights how a percentage of relatives are not “wonderful” and caring, but have “other motives”, which could put “enormous pressure” on many disabled people if assisted suicide was legalised.

He said: “Not everybody is a saint. This story is related to people trying to protect their inheritance and that could be a big issue for may disabled people.”

He pointed out that Lord Falconer, the most prominent cheerleader for legalisation, has admitted that he believes the real reason the law needs changing is to help people who cannot tolerate the idea of losing their independence.

Sir Bert said: “These are exactly the sort of people who come under severe pressure from their families.

“It is not only that they are likely to be living longer, but they could be spending the family income. If you’ve got more than 20-odd grand, you pay for your social care, so the strain on disabled people… is going to be enormous as they get older.

“You can see how families are going to say, ‘Well, we don’t want you to suffer, mum,’ thinking that what they don’t want to suffer is the bank account.

“What the KPMG report does, albeit with very small numbers – but you can extrapolate – is show that this is a real issue.”

Juliet Marlow, a postgraduate researcher and a member of the user-led network Not Dead Yet UK, which leads disabled people’s opposition to the Marris bill, said she had witnessed an older woman she had befriended being bullied by her son and social worker while on a specialist arthritis ward in hospital.

The woman wanted to stay in her own flat with the help of 24-hour personal assistants, but Marlow heard the social worker and the woman’s son telling her there was not enough funding for that and that it was best for her to sell her flat and move into residential care.

Marlow visited the woman in the care home about a month after discharge from the ward, and found her stuck upstairs in a tiny room, with a bath she couldn’t use.

She said: “She said she only saw people when they brought her laundry in or plonked food on her bedside table. She had lost a significant amount of weight and died shortly afterwards.

“I believe the care home’s lack of support brought on her death earlier than if she had been in her own home. Leaving a larger amount of money in her estate to pass on to her son, presumably.

“But in reality I suspect it was just that he couldn’t be bothered to take care of her himself.

“I think the problem is very few people are open about the fact they don’t want to ‘waste’ their parents’ money on care.

“Their coercion comes in the form of ‘we only want what’s best for you’ conversations, which puts a huge amount of pressure on elderly folk to succumb and do what their children want, even though it often brings on an earlier death.”